B3 Flashcards
(50 cards)
What is osmosis
Net movement of water from an area of higher water potential to an area of lower water potential
Diffusion of water
Down a concentration gradient
Across a partially permeable membrane
What is a turgid cell?
Water enters by osmosis, vacuole swells and pushes against cell wall
What is a flaccid cell?
Water lost from cell, vacuole shrinks, cell loses shape
What is active transport?
Does require energy
Particles move against a concentration gradient
Movement of particles from an area of lower concentration to an area of higher concentration-therefore it requires energy
The energy is needed to make “pumps” move particles the wrong way
Movement of substances against a concentration gradient across a partially permeable membrane
What is diffusion?
Net movement of particles from an area of higher concentration to lower concentration area
Down a concentration gradient (difference in number of particles on either side)
What affects the rate of diffusion?
Surface area
Concentration gradient
Thickness of gas exchange surface
How is the blood capillary involved in diffusion in the gut?
Dense capillary network-inside each villus are many capillaries which take away the absorbed molecules
How is the epithelial membrane involved in diffusion in the gut?
Is a thin layer(only one cell thick). This provides a short diffusion path for digested food molecules
How is the lacteal involved in diffusion in the gut?
At the centre of the villus absorbed fats and carries them away from the villus. This maintains concentration gradient for absorption
Why does the rate of active transport depends on the rate of respiration, why?
As more respiration occurs, more energy is available and therefore more active transport takes place
State the ventilation path
Nose + mouth Trachea Bronchus Bronchiole Alveoli Blood
What is ventilation?
Scientific term for breathing where air is constantly moving in and out of the lungs
What is inspiration?
Occurs when air pressure in the atmosphere is greater than that of the lungs forcing the air into the alveoli
What is expiration?
Occurs when air pressure in the lungs is greater than that in the atmosphere forcing air out the alveoli
What are xylem?
Cells that transport water and minerals up the stem from the roots to the shoots and leaves. This transport occurs in one direction only
What is phloem
Cells transport sugars produced in the leaves up and down the stem to growing and storage tissues
How are the phloem and xylem arranged
In plants as vascular bundles
Both form continuous systems connecting roots, stems and leaves
What is transpiration
The release of water vapour from a plant through the leaves causing water to move through the plant
What is stage one of transpiration
Water diffuses through osmosis from soil to roots
Roots are covered in tiny projections called root hair cells
These structures increase the surface area of he roots and therefore increases the rate of water up take/ diffusion by osmosis
What is stage two of transpiration
Water travels up the stem in the xylem
It diffuses from an area of high concentration to an area of low concentration
It’s higher in the roots because that’s where the water is absorbed it’s lower in the leaves because it’s used for photosynthesis
What is stage three of transpiration
Water travels through veins into leaves. It then diffuses out of the veins and into cells and from these airspaces, water diffuses by osmosis through the stomata into the air where it is evaporated
What is stage four of transpiration
The loss of water through transpiration in the leaves sets up a concentration gradient, continuously pulling water from the soul into all parts of the plant. Capillary action also encourages the water movement up the plant
What factors affect transpiration
Light intensity
Temperature
Humidity
Wind
What makes up the blood
Plasma
Platelets
White blood cells
Red blood cells
